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Thread: Measuring PH accurately

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    mitch08's Avatar
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    Measuring PH accurately

    I'm having a difficult time getting an accurate reading of my PH.
    I mean, I never thought I was color blind until I try telling the difference between 7.4, 7.6, and 7.8. They are soooo close.

    I feel like there is a big difference and Im thinking that mine might be dark enough to be 7.8. But Im not sure. Is there a trick or different test to find out exactly what it is?

    The chlorine test is the same to me. All those yellows look identical to me
    The difference with the chlorine is that I have the 100 test kit which is amazing and I just do the chlorine drop test and find out exactly what is going on. For instance, the other day I thought my FC was over 5 from the yellow test. It seemed dark. But that didnt make sense so I grabbed the chlorine drop test and it was 3.5 which was perfect.

    But I cant do that with PH.......

    Any advise on this?

    Thanks guys!!!
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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    Re: Measuring PH accurately

    Hey,

    Short of a VERY expensive digital meter, you just have to "wing it".

    Getting someone else's opinion or practicing several times is always a good idea.

    Fortunately, the difference between 7.3 and 7.6 is of virtually no consequence for our purposes with pools so if you get close, you're fine.
    Dave S.
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    Re: Measuring PH accurately

    Glad my daughter is home for the summer (young eyes)!
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    Re: Measuring PH accurately

    A little trick I learned a long time ago from an old timer whose eyes were about the same as mine now was to read the color scale in front of a grey scale panel, he actually used a newspaper which had a large section of grey area on it. Today I use a photo grey panel that I use for photography behind the scale since I have a few of them and use them for the photo hobby but really anything that adds a grey tint works well for distinguishing color levels. It doesn't help with color distinction as much as it helps with darkness levels which is what is the hardest to see for tired/older eyes.

    Give it a try and make sure to use sunlight instead of incandescent or fluorescent light, see if it helps.
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    Re: Measuring PH accurately

    If you are using the OTO (yellow drop) chlorine test at the same time as the pH test, read pH first. Staring at the yellow before looking at the red/orange can change your perception due to color fatigue. (I had the same pH test go from 7.5 to about 7.9 after looking at the OTO.)
    --paulr
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    Re: Measuring PH accurately

    Quote Originally Posted by 4JawChuck
    A little trick I learned a long time ago from an old timer whose eyes were about the same as mine now was to read the color scale in front of a grey scale panel, he actually used a newspaper which had a large section of grey area on it. Today I use a photo grey panel that I use for photography behind the scale since I have a few of them and use them for the photo hobby but really anything that adds a grey tint works well for distinguishing color levels. It doesn't help with color distinction as much as it helps with darkness levels which is what is the hardest to see for tired/older eyes.

    Give it a try and make sure to use sunlight instead of incandescent or fluorescent light, see if it helps.
    I will definitely try that. It makes perfect sense actually. I have a home theater that I use a grey scale screen on because it helps with the darkness levels and color distinction

    Thanks for your help!!!!
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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    mitch08's Avatar
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    Re: Measuring PH accurately

    Quote Originally Posted by PaulR
    If you are using the OTO (yellow drop) chlorine test at the same time as the pH test, read pH first. Staring at the yellow before looking at the red/orange can change your perception due to color fatigue. (I had the same pH test go from 7.5 to about 7.9 after looking at the OTO.)
    --paulr
    That's interesting. I always do both tests at the same time and Im pretty sure I look at the Chlorine first just by habit. Ill try it that way and see if it makes a difference.

    Love the gray scale idea though.
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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    Re: Measuring PH accurately

    I have a grow light for starting plants indoors that helps me. I put the block under it with white background and the colors pop. I was suspicious at first so I would test the chlorine with the drop test and was dead on every time. They're cheap to boot at walmart.
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    Re: Measuring PH accurately

    phew, its not just me struggling with the pink/orange pH
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    Re: Measuring PH accurately

    I like the gray background suggestion.

    I find I get my best reading by holding the comparator block against bright blue sky.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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    Re: Measuring PH accurately

    I get my best results holding the block at arm's length with a white resin patio chair as the background and squinting until the numbers are unreadable. I can tell if I'm closer to 7.5 or 7.8 no problem.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: Measuring PH accurately

    Blue sky works best for me, but I think it is a matter of finding a technique and then sticking with it over and over and you will get proficient.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Measuring PH accurately

    The FC/pH test kits include a white blotting cloth. I never use it and just save it to hold behind the tubes so I have a nice white background. And, as others have said I read it in natural light. It is amazing how much different the colors look under natural, incandescent or fluorescent lighting.
    Vince L

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    Re: Measuring PH accurately

    the colors going from low pH to high pH are....

    yellow 6.8 and lower
    yellow orange 7.0
    orange 7.2
    orange red 7.4-7.5
    red 7.6-7.8
    red violet 8.0
    violet 8.2 and higher

    These threads come up often.....naming the colors seems to help some folks.
    Dave S.
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    Re: Measuring PH accurately

    I use the white brick of my house. I have considered buying an electronic meter...but that will take significant research before I jump.
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
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    Re: Measuring PH accurately

    An electronic pH meter is not all that expensive. A low end model can be had for under $20. You will of course have to calibrate it on a regular basis.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    Re: Measuring PH accurately

    Quote Originally Posted by dschlic1 View Post
    An electronic pH meter is not all that expensive. A low end model can be had for under $20. You will of course have to calibrate it on a regular basis.
    How do you calibrate it? I was given one without operating manual.

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    Re: Measuring PH accurately

    The least expensive electronic meters can't be calibrated, and so are useless. The mid-rage ones all use different sequences to calibrate, so you need to find a copy of the manual (often available online).

    I would not trust a PH meter that costs less than $100. It might work for a while, but the less expensive ones are amazingly unreliable. They provide the illusion of precision, while lacking any true dependability.

    Unless you have significant color blindness, or need to measure PH several times a day every day, the color matching PH test really is your best choice. The extra effort required to keep the electronic meters in calibration is more trouble than it is worth otherwise.
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    Re: Measuring PH accurately

    For years now I have used the Lamotte ColorQ. It is very good and I do check from time to time with a regular test kit and I have to say, it's always close if not almost right on the money.
    Paul
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    Re: Measuring PH accurately

    There needs to be a TFP youtube vid on how to post youtube vids, lol.
    Is this a decent brand? are those pills still good?
    Heres the link http://youtu.be/vvNIGh-qZek

    - - - Updated - - -

    Quote Originally Posted by ps0303 View Post
    For years now I have used the Lamotte ColorQ. It is very good and I do check from time to time with a regular test kit and I have to say, it's always close if not almost right on the money.
    So out of the two what one would be the definite reading?

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